python API whoami

import getpass
print getpass.getuser()

See the documentation of the getpass module.

getpass.getuser()

Return the “login name” of the user. Availability: Unix, Windows.

This function checks the environment variables LOGNAME, USER, LNAME and USERNAME, in order, and returns the value of the first one which is set to a non-empty string. If none are set, the login name from the password database is returned on systems which support the pwd module, otherwise, an exception is raised.